KVM: SVM: Fix sev_pin_memory() error checks in SEV migration utilities

Use IS_ERR() instead of checking for a NULL pointer when querying for
sev_pin_memory() failures.  sev_pin_memory() always returns an error code
cast to a pointer, or a valid pointer; it never returns NULL.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Steve Rutherford <srutherford@google.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Fixes: d3d1af85e2c7 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command")
Fixes: 15fb7de1a7f5 ("KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210506175826.2166383-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 3dc3e28..02d60d7 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1271,8 +1271,8 @@ static int sev_send_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
        /* Pin guest memory */
        guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
                                    PAGE_SIZE, &n, 0);
-       if (!guest_page)
-               return -EFAULT;
+       if (IS_ERR(guest_page))
+               return PTR_ERR(guest_page);
 
        /* allocate memory for header and transport buffer */
        ret = -ENOMEM;
@@ -1463,11 +1463,12 @@ static int sev_receive_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
        data.trans_len = params.trans_len;
 
        /* Pin guest memory */
-       ret = -EFAULT;
        guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
                                    PAGE_SIZE, &n, 0);
-       if (!guest_page)
+       if (IS_ERR(guest_page)) {
+               ret = PTR_ERR(guest_page);
                goto e_free_trans;
+       }
 
        /* The RECEIVE_UPDATE_DATA command requires C-bit to be always set. */
        data.guest_address = (page_to_pfn(guest_page[0]) << PAGE_SHIFT) + offset;